1. Field of the Invention
This invention relates to moisture collection on the external surfaces of an air conditioning unit and more particularly to an apparatus and method for providing means to warm condensate formed on an evaporator as the condensate travels from the evaporator section to the condenser section of a room air conditioner.
2. Description of the Prior Art
In a typical room air conditioner a partition divides the unit into an evaporator section in communication with the environs to be cooled and a condenser section in communication with the outdoor ambient air. The unit typically has a vapor compression refrigeration circuit consisting of a compressor, condenser located in the condenser section, an expansion valve and an evaporator. The condensed liquid refrigerant is flashed from a liquid to gaseous state in the evaporator absorbing heat from the room air flowing over the evaporator and consequently cooling said air. During this process of flashing, heat is absorbed from the air and consequently its temperature is lowered thereby decreasing the amount of water that may be contained within the room air. The excess moisture that is no longer contained within the air is deposited on the evaporator surface as condensate. This condensate falls by gravity to the bottom of the unit and is conventionally collected in the condensate drain pan.
From the condensate drain pan the condensate at or near the relatively cold evaporator temperature is conducted through an opening in the partition to the condenser section. Once the condensate is within the condenser section it may be removed from the unit by simply draining it away, by use of a mechanical slinger or aspirator to place the condensate into the condenser fan airstream and consequently out of the unit through the condenser, said condensate acting to improve the efficiency of the condenser by evaporating and absorbing heat therefrom or the condensate may be retained within the condenser section of the unit until such time as it naturally evaporates.
Various methods of preventing moisture condensation or "sweating" on the exterior of the unit have been utilized. This sweating problem is caused by the cold condensate from the evaporator being conducted into the condenser section of the unit. Once within the condenser section this cold condensate which is at a much lower temperature than the ambient air causes localized portions of the condenser section to be lowered in temperature. Once these portions are lowered in temperature below the dew point of the ambient air in contact with that portion of the condenser section moisture is formed on the exterior of the unit. This moisture is unwanted and may cause dripping or other moisture problems which result when water that is difficult to funnel or drain away is collected. Often in an exterior mounted window unit this water simply drips and depending on the location may fall on a sidewalk or other pedestrian area.
The methods used to eliminate this sweating problem have included insulating the base pan in the condenser section of the unit such that there is thermal insulation between the cold condensate and the exterior surface of the unit. This does prevent sweating from occurring. Another method as disclosed in U.S. Pat. No. 4,107,939 entitled "Apparatus For Reducing External Condensate In An Air Conditioning Unit" discloses the use of air pressure differentials within the condenser section of the unit to cause the collected condensate to circulate. Hence, the condensate that has been warmed in the condenser section is mixed with the cold condensate and consequently the average temperature is such that no sweating occurs. The herein described method and apparatus provides for the cold condensate to be warmed prior to its entering the condenser section of the unit. Various flow barriers are utilized such that the condensate follows a tortuous path absorbing heat from the material in which it is in contact and from the ambient air circulated between the evaporator scroll and the partition for the purpose of transferring heat to the condensate.